Imaging the high-frequency charging dynamics of a single impurity in a semiconductor on the atomic scale

Maialen Ortego Larrazabal; Jiasen Niu; Stephen R McMillan; Paul M Koenraad; Michael E Flatté; Milan P Allan; Ingmar Swart

doi:10.48550/arxiv.2603.13040

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Imaging the high-frequency charging dynamics of a single impurity in a semiconductor on the atomic scale

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Imaging the high-frequency charging dynamics of a single impurity in a semiconductor on the atomic scale

Maialen Ortego Larrazabal, Jiasen Niu, Stephen R McMillan, Paul M Koenraad, Michael E Flatté, Milan P Allan and Ingmar Swart

ArXiv.org

Cornell University

03/13/2026

DOI: 10.48550/arxiv.2603.13040

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Preprint (Author's original)This preprint has not been evaluated by subject experts through peer review. Preprints may undergo extensive changes and/or become peer-reviewed journal articles. Open Access

Abstract

As electronic devices approach the atomic limit, the charge dynamics of individual dopant atoms increasingly constrain performance, stability, and coherence. In scanning tunnelling microscopy (STM), donor ionization is typically interpreted as a static threshold process arising from tip-induced band bending. Here we show that the ionization of individual sulfur donors in InAs is intrinsically dynamic and governed by the local electric field. Using MHz-frequency STM noise spectroscopy with atomic-scale spatial mapping, we resolve pronounced random telegraph noise that is invisible in time-averaged tunnelling spectra. A bias-dependent model quantitatively links the noise spectra to microscopic ionization and neutralization processes of the donor states, enabling direct extraction of nanosecond charge-state lifetimes. The switching rate is strongly bias dependent, demonstrating that the electric field continuously drives charge-state transitions. Unexpectedly, we show that the degenerately doped bulk leads to a sharp bias-dependent onset of donor ionization as the donor level crosses the Fermi level, giving rise to a characteristic shoulder in the noise power spectrum that is captured by our model. These results establish donor ionization as a non-equilibrium dynamical process with nontrivial contribution by the bulk electrons, and identify impurity switching as a universal nanoscale charge-noise mechanism relevant to quantum devices.

Physics - Materials Science

Physics - Mesoscale and Nanoscale Physics

Details

Title: Subtitle: Imaging the high-frequency charging dynamics of a single impurity in a semiconductor on the atomic scale
Creators: Maialen Ortego Larrazabal
Jiasen Niu
Stephen R McMillan
Paul M Koenraad
Michael E Flatté
Milan P Allan
Ingmar Swart
Resource Type: Preprint
Publication Details: ArXiv.org
DOI: 10.48550/arxiv.2603.13040
ISSN: 2331-8422
Publisher: Cornell University; Ithaca, New York
Language: English
Date posted: 03/13/2026
Academic Unit: Electrical and Computer Engineering; Physics and Astronomy
Record Identifier: 9985147207102771

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